Hi Is it safe for baby 4 months plus to wear mittens to bed? My baby wants his hands in his mouth all the time and has started pulling his sleeping sack over his face.

It is not uncommon for babies to want to touch their face or suck on fingers as part of soothing or settling.
Some mittens may be made of material where baby could suck off some of the material.

Is he rolling yet?
Is he in a cot or bassinet?